Hubs
At the bottom of the networking food chain, so
to speak, are hubs. Hubs are used in networks that use twisted-pair
cabling to connect devices. Hubs can also be joined together to
create larger networks.
Hubs
are simple devices that direct
data packets to all devices connected to the hub, regardless of
whether the data package is destined for the device. This makes
them inefficient devices and can create a performance bottleneck on
busy networks.
In its most basic form, a hub does nothing
except provide a
pathway
for the electrical signals to travel
along. Such a device is called a
passive
hub. Far more
common nowadays is an
active
hub, which, as well as
providing a
path
for the data signals, regenerates the signal
before it forwards it to all of the connected devices. A hub does
not perform any processing on the data that it forwards, nor does
it perform any error checking.
Hubs come in a variety of
shapes
and sizes.
Small hubs with five or eight connection ports are commonly
referred to as
workgroup hubs
.
Others can accommodate larger
numbers
of devices (normally up to
32). These are referred to as
high-density
devices
. Because hubs don't
perform any processing, they do little except enable communication
between connected devices. For today's
high-demand
network
applications, something with a little more intelligence is
required. That's where switches come in.
|
Bird, Drew
and Harwood, Mike.